Carbon Black Reinforced Compositions

ABSTRACT

This disclosure relates to the use of a certain class of carbon black pigments as reinforcing agents in the preparation of rubber compositions having improved properties.

Jordan et a1.

CARBON BLACK REINFORCED COMPOSITIONS Inventors: Merrill E. Jordan,Walpole; William G. Burbine, Whitman; Frank R. Williams, Quincy, all ofMass.

Assignee: Cabot Corporation, Boston, Mass.

Notice: The portion of the term of this patent subsequent to Mar. 26, a,a a 1991. has been dis laimedt.

Filed: Apr. 2, 1973 Appl. No.: 346,979

[ *Feb. 4, 1975 [56] References Cited UNITED STATES PATENTS 3,443,9015/1969 Wendell et a1 260/415 R 3,595,618 6/1971 Kiyonaga et al. 260/415R 3,619,140 11/1971 Morgan et al 260/415 R Primary Examiner-MorrisLiebman Assistant ExaminerW. H. Fletcher Attorney, Agent, orFirm-Kenneth W.- Brown; Barry R. Blaker; Lawrence A. Chaletsky [57]ABSTRACT This disclosure relates to the use of a certain class of carbonblack pigments as reinforcing agents in the preparation of rubbercompositions having improved properties.

10 Claims, No Drawings 1 CARBON BLACK REINFORCED COMPOSITIONS Thisinvention relates to new and useful natural and synthetic rubbercompositions. in particular,'this invention relates to new and improvedrubber compositions comprising a natural or synthetic'rubber and acertain class of carbon black products which improve the physicalproperties of the rubber to which it is added.

Normally, there have been widely employed as fillers and reinforcingpigments in the compounding and preparation of rubber compositionsvarious conventional carbon blacks known heretofore. Ordinarily, theconventional carbon blacks are effective in the preparation of rubbervulcanizates having improved reinforcement properties such as tensilestrength, modulus and treadwear. The improvement in properties exhibitedby an elastomeric article or rubber stock filled with a carbon blackwill depend to a great extent upon the type of elastomer utilized andthe particular carbon black incorporated therein. It has now been madepossible by using the carbon blackproducts of the present invention toprovide finished products having still further improved tensilestrength, modulus, abrasion resistance, and treadwear.

Accordingly, it is a principal object of this invention to provideimproved natural and synthetic rubber compositions.

lt is a further object of this invention'to provide a suitable carbonblack reinforcing additive for natural and synthetic rubbers whichimparts the desired properties to the resultant composition.

Other objects and advantages of the :present invention will be apparentto those skilled in the art from the following detailed description andclaims.

In accordance with this invention, it has been found that the above andstill further objects are accomplished by incorporating a certain classof novel carbon black products intoa natural or synthetic rubber.

Generally, amounts of the carbon black product ranging from about 10 toabout 250 parts by weight can be used for each 100 parts by weight ofrubber in order to impart a significant degree of reinforcement thereto.It is, however, preferred to use amounts varying from about 20 to about100 parts by weight of carbon black per 100 parts by weight ofrubber-and especially preferred is the utilization of from about 40 to80 parts of carbon black per 100 parts of rubber.

The rubbers for which the novel carbon blacks of this invention areeffective as reinforcing agents include natural and synthetic rubbers.Among the rubbers suitable for use with the present invention arenatural rubber and its derivatives such as chlorinated rubber;copolymers of from about l to about 70 percent by weight of styrene andfrom about 90 to about 30 percent by weight of butadiene such ascopolymer of 19 parts styrene and 81 parts butadiene, a copolymer of 30parts styrene and 70 parts butadiene, a copolymer of 43 parts styreneand 57 parts butadiene and a copolymer of 50 parts styrene and 50 partsbutadiene; polymers and copolymers of conjugated dienes such aspolybutadiene, polyisoprene, polychloroprene, and the like, andcopolymers of such conjugated dienes with an ethylenic group-containingmonomer copolymerizable therewith such as styrene, methyl styrene,chlorostyrene, acrylonitrile, 2-vinyl-pyridine, -methyl-2-vinylpyridine, 5-ethyl-2-vinylpyridine, 2-methyl-5- vinylpyridine,alkyl-substituted acrylates, vinyl ketone,

methyl isopropenyl ketone, methyl vinyl ether, alphamethylene carboxylicacids and the esters and amides thereof such as acrylic acid anddialkylacrylic acid amide; also suitable for use herein are copolymersof ethylene and other high alpha olefins such as propylene, butene-l andpentene-l; particularly preferred are the ethylene-propylene copolymerswherein the ethylene content ranges from 20 to percent by weight andalso the ethylene-propylene polymers which additionally contain a thirdmonomer such as dicylopentadiene, l, 4-hexadiene and methylenenorbornene.

The reinforcing agent utilized in the rubber compositions of the presentinvention include a novel group of carbon blacks which are of thefurnace process type, are non-aftertreated. havev a pH value of at least4.0, an iodine surface area ranging from at least 67 to about m /g, atint factor value,-represented by the relationship of [tint 0.6 (D,,)],of at least 3ll to 316. a BET nitrogen surface area of less than m /g,and a value for the tint contribution, which is defined as the ratio oftint to tint factor, varying from at least 0.75 to 0.82. In determiningthe value for the tint factor of the blacks, D the apparent diameter, isdefined as the diameter, in millimicrons, of a solid carbon spherecontaining the same amount of carbon as the average amount of carbon peragglomerate in a paper by Avrom l. Medalia and L. Willard Richardsentitled Tinting Strength of Carbon Black" presented to the AmericanChemical Society, Division of Coatings and Plastic Chemistry, Toronto,Canada, May l970. For purpose of this invention, the apparent diameter,D,,, is obtained from the calculation [2270 63.5 (DBP)]llodine SurfaceArea. if desired, the carbon blacks herein may be described in terms ofpercent tint contribution by multiplying the value for the ratio of tintto tint factor by 100.

in the preparation of the hot combustion gases employed in preparing thenovel type of carbon black products of the present invention, there arereacted in any conventional combustion chamber a liquid or gaseous fueland, a suitable oxidant stream such as air, oxygen, mixtures of air andoxygen or the like. Among the fuels suitable for use in reacting withthe oxidant stream in the combustion chamber to generate the hotcombustion gases are included any of the readily combustible gas, vaporor liquid streams such as hydrogen, carbon monoxide, methane, acetylene,alcohols, kerosene. It is generally preferred, however, to utilize fuelshaving a high content of carbon-containing components, and, inparticular, hydrocarbons. For example, streams rich in methane such asnatural gas and modified or enriched natural gas are excellent fuels aswell as other streams containing high amounts of hydrocarbons such asvarious petroleum gases and liquids and refinery by-products includingethane, propane, butane and pentane fraction, fuel oils and the like.The carbon black products ofthe present invention are prepared byreacting the aforementioned combustion reaction products with any of awide variety of hydrocarbon feedstocks.

Accordingly, in greater detail, the novel carbon black products areprepared by reacting a carbon blackyielding hydrocarbon feedstock withhot gaseous products of an initial combustion reaction which are flowingat a high linear velocity in a suitable reaction zone. The hotcombustion gases are readily generated by contacting a combustible fuelwith an amount of oxidant, such 3 as air or oxygen, which, if desired,may be preheated varying from about 50 to about 500 percent of theamount required for complete combustion of thecombustible fuel to thedesired hot gaseous products in any type of conventionally known burnerdesigned to produce a stream of hot combustion gases flowing at a highlinear velocity. It is, furthermore, desirable that there be a pressuredifferential between the combustion chamber and the reaction chamber ofat least 1.0 p.s.i., and more preferably, of about 1.5 to about psi.Under these conditions, there is produced a stream of gaseous combustionproducts possessing sufficient energy to convert a carbon black-yieldinghydrocarbon feedstock to the desired carbon black products. Theresultant combustion gases emanating from the combustion zone attaintemperatures of at least about 2400F, and in most instances thetemperature is in excess of about 3000F. The hot combustion gases flowin a downstream direction at a high linear velocity which may beeffectuated by passing the combustion gases through any suitable passageor inlet which may optionally be tapered or restricted such as aconventional venturi throat. There is then introduced into the stream ofhot combustion gases traveling at a high velocity at a point where thereexists a pressure differential between the combustion chamber and thereaction chamber of above about 1.0 p.s.i., a suitable carbonblack-yielding hydrocarbon feedstock thereby insuring a high rate ofmixing and shearing of the hot combustion gases and the hydrocarbonfeedstock so as to rapidly and completely decompose and convert thefeedstock to the novel carbon blacks in high yields. The hydrocarbonfeedstock is injected substantially transversely from the periphery ofthe stream of hot combustion gases in the form of a single or preferablya plurality of small, coherent jets which penetrate into the interiorregions of the stream of combustion gases. The amount of feedstockutilized will be adjusted in relation to the amounts of fuel and oxidantemployed so as to result in an overall percent combustion for theprocess ranging from about 12 to about 65 percent and, preferably, fromabout to about 50 percent. Following the period of reaction in thereaction zone, which may vary from about 1 to about 100 milliseconds, oreven shorter periods of time, the effluent g'ases containing the desiredcarbon black products suspended therein are passed downstream to anyconventional cooling and separating means whereby the carbon blacks arerecovered. The separation of the carbon black from the gas stream isreadily accomplished by conventional means such as a precipitator,cyclone separator and bag filter.

The following test procedures are used in the determination andevaluation of the physical properties and efficiency of the carbonblacks of the present invention.

In the following procedures, the analytical properties are determinedusing the pelleted form of the carbon blacks. In the event the blacksare to be used in an application where the fluffy form is desired, thena portion of the fluffy black is pelletized for purposes ofcharacterizing the blacks in accordance with the, test procedureshereinbelow.

DBP Absorption In accordance with the procedure set forth in ASTMD-2414-65T. now designated as ASTM D-2414-70, absorption characteristicsof pelleted carbon blacks are determined. In brief. the test procedureentails adding dibutyl phthalate DBP) to a pelleted carbon black untilthere occurs a transition from a free-flowing powder to a semi-plasticagglomerate. The value is expressed as cubic centimeters (c.c.) ofdibutyl phthalate (DBP) per 100 grams of carbon black.

lodine Surface Area The surface area of pelletized carbon black productsis determined in accordance with the following iodine adsorptiontechnique. In this procedure, a carbon black sample is placed into aporcelain crucible equipped with a loose-fitting cover to permit escapeof gases and is devolatilized for a 7- minute period at a temperature of1700F in a muffle furnace and then allowed to cool. The top layer ofcalcined carbon black is discarded to a depth of one fourth inch and aportion of the remaining black is weighed. To this sample there is addeda 100 milliliter portion of 0.01 N iodine solution and the resultingmixture is agitated for 30 minutes. A 50-milliliter aliquot of themixture is then centrifuged until the solution is clear, following which40 milliliters thereof is titrated, using a 1% soluble starch solutionas an end point indicator, with 0.01 N sodium thiosulfate solution untilthe free iodine is adsorbed. The percent of iodine adsorbed isdetermined quantitatively by titrating a blank sample. Finally, theiodine surface area expressed in square meters per gram is calculated inaccordance with the formula [(72 lodine Adsorbed X 0937) 4.51/SampleWeight lodine Surface Area This procedure for determining iodine surfaceareas of carbon black pellets is designated as Cabot Test Procedure No.23.1 for purposes of convenience inasmuch as there is still no officialASTM designation. As shown in a Cabot Corporation publication TG--1entitled Industry Reference Black No. 3 by Messrs. .luengel and OBrienpublished on April 1, 1970, the iodine surface area of [RB No. 3(Industry Reference Black No. 3) is 66.5 m /g as determined inaccordance with Cabot Test Procedure 23.1 referred to hereinabove.

Tinting Strength Tinting strength represents the relative covering powerof a pelletized carbon black when incorporated in a l to 37.5 weightratio with a standard zinc oxide (Florence Green Seal No. 8 made andsold by New Jersey Zinc Co.), dispersed in an epoxyized soybean oil typeplasticizer (Paraplex G-62 made and sold by Rohm and Haas Co.) andcompared to a series of standard reference blacks tested under the sameconditions. More particularly, the test involves mulling carbon black,zinc oxide, and plasticizer, in such proportions that the resultingratio of carbon black to zinc oxide is 1 to 37.5. Reflectancemeasurements utilizing a Welch Densichron apparatus are then obtainedfrom a film cast on a glass plate and readings are compared to carbonblack standards having known tinting strengths. The tinting strengths ofthe carbon black standards are determined utilizing an arbitrarilyassigned value of for the tinting strength of the Cabot standard SRFcarbon black. In this instance, as is conventionally done, the standardSRF carbon black arbitrarily assigned a value of 100% for tintingstrength is Sterling S or Sterling R semi-reinforcing furnace black madeby Cabot Corporation. Each of the Sterling R or Sterling S referenceblacks is characterized by having, among other properties, a BETnitrogen surface area of about 23 m /g, an oil absorption of about 65 tov70 lbs. oil/100 lbs. black, and an average particle diameter of about800 angstroms as determined by electron microscopy. The only differenceis that Sterling R carbon black is in a fluffy form while the Sterling Scarbon black is in pelleted form. Accordingly, the black selected forreference purposes then is deter- 5 mined by the state ofthe blacks tobe measured for tinting strengths. The Sterling R or Sterling Ssemireinforcing carbon black is thus considered as the primary referencestandard for determining tinting strengths of the other blacks.

Furthermore, as described above, additional carbon blacks are utilizedas references for establishing tinting strength values covering therange of about 30% to about 250 percent. These are determined relativeto the primary standard having the arbitrarily assigned value of 100%for tinting strength. In this manner, a series of blacks having a widerange of tinting strengths is made available so as to provide referenceblacks that approximate as closely as possible the black to be measured.Exemplary carbon blacks employed as auxiliary 20 tinting strengthstandards for purposes of the above procedure include the followingblacks made by Cabot Corporation. The analyticals are determined inaccordance with the test procedures set forth in the present 6 black no.D-6607 having an arbitrarily assigned value of 100 percent. M

In carrying out the above roadwear evaluations there is used thefollowing fomulation of ingredients. expressed in parts by weight. whichare admixed by means of a Banbury mill.

With regard to the foregoing formulation for use in road tests,designated hereinafter as RTF-l Santocure (CBS) is the trade designationfor N-cyclohexyl-2- benzothiazole-sulfenamide, a curing agent for rubbersystems; Sundex 790 is the trade name for a plasticizer application.sold by Sun 011 Company; Sunproof lmproved IS the Sterling MT SterlingFT Analytical (Medium (Fine Properties Thermal) Thermal) Vulcan 6HVulcan 9 Tinting Strength.

Iodine Surface Area, mlg 5.0 8.4 109.6 118.5

DBP Absorption,

cc/ g 33.6 35.9 131.4 116.9

For purposes of reference, the tinting strength of lRB No. 3 asdetermined in accordance with the above procedure is 208% of the primarySterling S semireinforcing black. This is also disclosed in the earliermentioned publication on Industry Reference Black No. 3 by Messrs..luengel and OBrien.

Roadwear Rating The procedure for measuring and evaluating roadwear ortreadwear is well known to the art and is completely described in CabotCorporations Technical Service Report No. TG-67-l on The Use ofMulti-Section Treads in Tire Testing by Fred E. Jones (1967). It is tobe noted that, as in the case of any procedure for measuring wearratings, the evaluations are made relative to a standard reference blackwhich is arbitrarily assigned a wear rating value of 100 percent. lnthis instance, the black selected as the reference standard forevaluating roadwear is an lSAF (intermediate super abrasion furnace)type black, having an ASTM designation of N-220, made by CabotCorporation and further characterized by having a tinting strength of232%, an iodine surface area of 97.9 m /g, a DBP absorption of 1 14.9cc/100 g, and a density of 22.2 lbs./cu.ft. For ease of reference, thistreadwear reference black is described as Cabot's lSAF type referenceblack no. D-6607. The above method for determining relative wear ratingsof treadstocks is preferred to the use of laboratory tests for measuringabrasion since it is known to be-difficult to extrapolate such resultsto actual performance. Accordingly, the roadwear results shown hereinreflect accurately the performance of treadstocks relative to Cabotsstandard lSAF type trade name for an antiozonant sold by UniroyalChemical Company; and Wingstay 100 is the trade name for a stabilizercomprising mixed diaryl-p-phenylene diamines sold by Goodyear Tire andRubber Company.

Total Surface Area The total surface area of the carbon blacks ismeasured in accordance with the wellknown BET technique utilizingnitrogen isotherms. The BET (Brunauer-Emmet-Teller) method is completelydescribed in an article appearing in the Journal of the AmericanChemical Society, Vol. 60, page 309 (1938). Surface areas obtained inthe usual manner by the BET technique include the external surface areaas well as the internal surface area contributed by the presence ofpores.

Rebound This is determined in accordance with the procedure set forth inASTM D'1054-66.

The invention will be more readily understood by reference to thefollowing examples which describe the detailed preparation ofrepresentative compounds. There are, of course, many other forms of thisinvention which will become obvious to one skilled in the art, once theinvention has been fully disclosed, and it will accordingly berecognized that these examples are given for the purpose of illustrationonly, and are not to be construed as limiting the scope of thisinvention in any way.

EXAMPLE 1 In this example there is employed a suitable reactionapparatus provided with means for supplying the combustion gas-producingreactants, i.e., a fuel and an oxidant stream, either as separatestreams or as precombusted gaseous reaction products; and also means forsupplying the carbon black-yielding hydrocarbon feedstock to theapparatus. The apparatus may be constructed of any suitable materialsuch as metal and either provided with a refractory insulation orsurrounded by means for cooling such as a recirculating liquid which ispreferably water. Additionally, the reaction apparatus is equipped withtemperature and pressure recording means, means for quenching the carbonblack-forming reaction such as spray nozzles, means for cooling thecarbon black product and means for separating and recovering the carbonblack from other undesired by-products. Accordingly, in carrying out thepresent process for preparing the novel carbon blacks, the followingprocedure is employed. ln order to obtain the desired flame, there arecharged into a combustion zone of the apparatus through one or more Iinlets oxygen at a rate of 2000 SCFH and natural gas at a rate of 625SCFH thereby generating a stream of combustion gases flowing in adownstream direction at a high linear velocity which possesses a kinetichead of at least 1.0 p.s.i. greater than the pressure of the reactionchamber. Accordingly, in a preferred embodiment of the presentinvention, the rapidly flowing stream of combustion gases is passedthrough a constricted or tapered portion of the apparatus having a fixedcross section or throat such as a conventional venturi throat in orderto increase the linear velocity of the stream of combustion gases. Thereis then introduced transversely into the resultant stream of hotcombustion gases having the desired kinetic head a carbon blackyieldinghydrocarbon feedstock through one or more passages or inlets locatedperipherally to the stream of combustion gases at a rate of 16.2 gallonsper hour. The feedstock used is Sunr'ay DX which is a fuel having acarbon content of 91.1% by weight, a hydrogen content of 7.9% by weight,a sulfur content of 1.3% by weight, a hydrogen to carbon ratio of 1.04,a B.M.C.l. Correlation Index of 133, a specific gravity in accordancewith ASTM D-287 of 1.09, an API gravity in accordance with ASTM D-287 of2.6, an SSU viscosity (ASTM D-88) at 130F of 350, an SSU viscosity (ASTMD-88) at 2l0F of 58 and an asphaltenes content of5.7 percent. Thereaction conditions used in this instance are such as to provide anoverall combustion of 30.3 percent. The carbon black forming reaction isthen quenched with water to a temperature of 900F in a separate zonedownstream of the reaction zone and the resultant carbonblack-containing gases are subjected to the conventional steps ofcooling, separation and recovery of the carbon black product in a yieldof 4 pounds per gallon of fuel. The carbon black product thus obtainedis characterized by having a tint value of 257%, an iodine surface areaof 129 m /g, a DBP absorption value of 155, a pH of 6.5, an apparentdiameter, D,,, of 93.9, a value for the tint factor relationship of[tint 0.6 (D,,)] of 313.3, a BET nitrogen surface area of 146 m' /g, anda value for the ratio of tint to tint factor of 0.82.

EXAMPLE 2 A suitable reaction apparatus as described in Example l ischarged with oxygen at a rate of 2000 SCFH and natural gas at a rate of360 SCFH in order to produce a suitable flame for carrying out thereaction. .To the downstream-flowing combustion gases which have beenpassed through a constricted or tapered portion of the apparatus thereis then fed the Sunray DX hydrocarbon feedstock at a rate of 19.2gallons per hour. In this run, the reaction conditions are maintained ina manner such as to provide an overall combustion of 27 percent and thereaction is quenched with water to a temperature of 684F. At theconclusion of the reaction there is produced in a yield of 3.6 poundsper gallon of fuel a carbon black product having a tint value of 242%,an iodine surface area of 103 m /g, a DBP absorption value of 164, anapparent diameter, D,,. of 123.1, a value for the tint factorrelationship [tint 0.6 (D,,)] of3 16, a pH value of 6.8, a BET nitrogensurface area of 1 l8 m /g, and a value for the tint contribution ratioof tint to tint factor of 0.77.

EXAMPLE 3 In accordance with the procedure of Example 1, air preheatedto 760F at a rate of 340,000 SCFH and natural gas at a rate of 23,800SCFH are fed into the combustion zone of the reaction apparatus. To theresultant downstream flow of hot combustion gases there is charged Enjayhydrocarbon feedstock under a pressure of 228 p.s.i.g. at a rate of 533gallons per hour. Prior to adding the feedstock, potassium chloride isadded to the stream of hot combustion gases in an amount of4.3 grams pergallons fuel. In more detail, the Enjay hydrocarbon feedstock employedis a fuel having a carbon content of 89.8% by weight, a hydrogen contentof 8.6% by weight, a sulfur content of 1.5% by weight, a hydrogen tocarbon ratio of 1.15, a B.M.C.l. Correlation Index of 123, a specificgravity in accordance with ASTM D-287 of 1.08, an API gravity inaccordance with ASTM D-287 of 0.3, an SSU viscosity (ASTM D-88) at F of569.2, an SSU viscosity (ASTM D-88) at 2l0F of 67.5 and an asphaltenescontent of 0.6 percent. The reaction is carried out at an overallcombustion of 31.8 percent and the reaction is quenched with water to atemperature of 1400F. There is obtained, in a yield of 5 pounds pergallon of fuel oil, a carbon black product having a tint value of 239%,an iodine surface area of 74.6 m' /g, a DBP absorption value of l 12, apH of 6.7, an apparent diameter, D,,' of 126, a value for [tint 0.6(D,,)] of 314, a BET nitrogen surface area of 92 m /g, and a tintcontribution ratio of tint to tint factor of 0.76.

EXAMPLE 4 Following the procedure of Example 1 there are charged to acombustion zone a stream of air at a temperature of 760F at a rate of340,000 SCFH and a stream-of natural gas at a rate of 24,200 SCFH toproduce the desired flame. Into the gaseous products of the combustionreaction there is then fed under pressure of 250 p.s.i.g. as thehydrocarbon feedstock Enjay oil at a rate of 544 gallons per hour andthe reaction conditions are maintained so as to produce an overallcombustion of 3 1 .2 percent. During the preparation of the carbon blackof this example, which is produced in a yield of 5.3 pounds per gallonfuel oil, potassium chloride is added in an amount of 7.6 grams per 100grams of fuel oil and the reaction is quenched with water to atemperature of 1330F. The resultant carbon black product ischaracterized by having an iodine surface area of 69.5 m /gm, a DBPabsorption value of 108, a tint value of 237%, a pH of 7.0, an apparentdiameter, D,,, of 131, a tint factor value for [tint 0.6

(D,,)] of 3l6, a BET nitrogen surface area of 90 m' /g,

and a value for the ratio of tint to tint factor of 0.75.

EXAMPLE 5 Following the procedure of Example I, air preheated to 710F ata rate of 340,000 SCFH and natural gas at a rate of 24.000 SCFH are fedinto the combustion zone of the reaction apparatus. To the resultantdownstream flow of hot combustion gases there is charged Enjay oilfeedstock at a rate of 476 gallons per hour and under a pressure of 250p.s.i.g. The reaction is carried out at an overall combustion of 34.8percent and there is obtained in a yield of 5 pounds per gallon of fueloil a carbon black product having an iodine surface area of 78.6 m /g, aDBP absorption value of 121, a tint value of 240%, a pH of 6.7, anapparent diameter, D of 127, a tint factor value for [tint 0.6 (D,,)] of316, a BET nitrogen surface area of 102 m /g, and a value for the ratioof tint to tint factor of 0.76.

The suitability of the blacks of the present invention as reinforcingagents for rubber compositions is clearly shown by the followingexamples. In carrying out the examples, the rubber compositions arereadily prepared by conventional mechanical methods. For example, therubber and the carbon black reinforcing agent are intimately admixedtogether on a conventional mixing machine of the type normally used formixing rubber or plastics such as a Banbury mixer and/or a roll mill inorder to insure satisfactory dispersion. The rubber compositions arecompounded according to standard industry formulations for both anatural rubber and synthetic rubber-containing formulation. Theresulting vulcanizates to be tested are cured'at 293F for 30 minuteswhen natural rubber is used and for 50 minutes when a synthetic rubber,styrene-butadiene rubber in this instance, is employed. In evaluatingthe performance of the novel carbon blacks of the present invention, thefollowing formulations are utilized wherein the quantities are specifiedin parts by weight.

With regard to the above, Altax (MBTS) is the trade name of R. T.Vanderbilt Company for mercaptobenzothiazyl disulfide accelerator.Flexamine is the trade designation of an antioxidant sold by US. RubberCompany. Santocure (CBS) is the trade designation forN-cyclohexyl-2-benzothiazole-sulfenamide, a curing agent for rubbersystems. Sundex 790 is the trade name for a plasticizer sold by Sun OilCompany. Sunproof Improved is the trade name for an antiozonant sold byUniroyal Chemical Company. Wingstay 100 is the trade name for astabilizer comprising mixed diaryl-pphenylene diamines sold by GoodyearTire and Rubber Company.

In the following examples there is demonstrated the advantageous andunexpected results achieved by the use of the carbon black productsdescribed hereinabove as additives in rubber formulations. It will, ofcourse, be apparent that the examples, while being 11- lustrative of thepresent invention, should not be construed as limiting or restrictive inany way.

EXAMPLE 6 On a conventional roll mill there are mixed to a homogeneousblend parts by weight of natural rubber, 5 parts by weight of zincoxide, 3 parts by weight of stearic acid, 2.5 parts by weight of sulfur,0.6 parts by weight of mercaptobenzothiazyl disulfide (MBTS) and 50parts by weight of the carbon black prepared in accordance with Example2. The resulting compound is subsequently cured at 293F for a period of30 minutes. This formulation is referred to as the ASTM natural rubberrecipe. A determination of properties of the vulcanizate gives a valueof 49.3 for Mooney viscosity ML-4' at 250F, a tensile strength of 3720p.s.i., a 300% modulus of 2850 p.s.i., an elongation of 400%, and aShore hardness of 67.

EXAMPLE 7 Following the procedure of Example 6 and using in lieu of thecarbon black employed therein, 50 parts by weight of the carbon black ofExample 3, there is obtained a rubber compound having a 300% modulus of2566 p.s.i., a tensile strength of 4110 p.s.i., an elongation of 463%, aShore A hardness of 67.3, and :1 M00- ney viscosity ML-4 at 250F of41.6.

EXAMPLE 8 Following the procedure of Example 6 and substituting 50 partsby weight of the carbon black of Example 4 for the black used therein, avulcanizate is prepared. Results on this vulcanizate include a tensilestrength of 4102 p.s.i., a 300% modulus of 2500 p.s.i., an elongation of467%, a Shore A hardness of 66.2, and a Mooney viscosity ML-4 at 250F of40.6.

EXAMPLE 9 In accordance with the procedure of Example 6, a vulcanizateis prepared utilizing 50 parts by weight of the carbon black of Example5. Testing of the vulcanizate reveals a 300% modulus of 2691 p.s.i., atensile strength of 4379 p.s.i., an elongation of 488%, a Shore Ahardness of 67.1, and a Mooney viscosity ML-4' at 250F of 43.9.

EXAMPLE 10 100 parts by weight of a copolymer of 23.5 parts styrene and76.5 parts butadiene, 5 parts by weight of zinc oxide, 2 parts by weightof sulfur, 1.5 parts by weight of stearic acid, 2 parts by weight ofmercaptobenzothiazyl disulfide, and 50 parts by weight of the carbonblack of Example 2 are mixed on a roll mill to a homogeneous blenddesignated hereinabove as synthetic rubber recipe No. 1. This recipe isalso known as the ASTM standard industry synthetic rubber recipe.Following the normal 50 minute curing time, the vulcanizate is testedfor various physical properties. The determinations reveal a tensilestrength of 4470 p.s.i., a 300% modulus of 3250 p.s.i., an elongation of4l0% and a Shore A hardness of 67.

EXAMPLE 1 1 Following the procedure of Example and using for the carbonblack employed therein a carbon black as prepared in Example 3, there isobtained a cured synthetic rubber vulcanizate. The results obtained onthis vulcanizate show a 300% modulus of 2730 p.s.i., a tensile strengthof 4623 p.s.i., an elongation of 480%, a Mooney viscosity ML-4' at 2l2Fof 83.9 and a Shore A hardness of 70.

EXAMPLE l2 Following the procedure of Example 10 and using for thecarbon black employed therein a carbon black as prepared in Example 4,there is obtained a cured rubber vulcanizate. The results obtained onthis vulcanizate show a 300% modulus of 2622 p.s.i., a tensile strengthof 4608 p.s.i., an elongation of 480%, a Mooney viscosity ML-4' at 2l2Fof 81.7 and a Shore A hardness of 69.2.

of stearic acid, 1.75 parts by weight of sulfur. l.4 parts by weight ofSantocure (CBS) and 75 parts by weight of the carbon black prepared asshown in Example I. The results obtained on this vulcanizate cured for60 minutes give a value for Mooney viscosity ML-4 at 2 l 2F of 50, aMooney Scorch T5/Tl0 of l8/l9, an extrusion shrinkage of 37.9%, atensile strength of 2700 p.s.i., a 300% modulus of 1300 p.s.i., anelongation of 460% and a Shore hardness of 60.

EXAMPLE 15 For purposes of determining roadwear ratings, rubbervulcanizates of the formulation described fully hereinbefore areprepared utilizing each of the blacks prepared in Examples 1 through 5.Moreover, as mentioned in the test procedures for determining roadwearratings, the results are reported in the following TABLE I relative toCabots standard ISAF type black which is arbitrarily assigned a roadwearrating of I00 percent. Also included in TABLE I for purposes ofcomparison are roadwear ratings for a comprehensive group of rubbergrade carbon blacks made and sold by Cabot Corporation under the tradename Vulcan.

TABLE I Carbon Blacks made and sold by Cabot Corporation) EXAMPLE 13 Acured rubber vulcanizate is produced according to Example 10 with theexception that, for the carbon black utilized therein, 50 parts byweight of carbon black manufactured as described in Example 5 isemployed herein. Measurements on this vulcanizate reveal a Mooneyviscosity ML- 4 of 86.9 at 2l2F, a tensile strength of 4530 p.s.i., a300% modulus of 2901 p.s.i., and an elongation of 456%.

EXAMPLE 14 In this example there is utilized for rubber evaluationpurposes the formulation designated hereinbefore as synthetic rubberrecipe No. 2. In particular, there are mixed on a Banbury mixer at 150rpm to a homogeneous blend 89.38 parts by'weight ofa copolymer of 23.5parts styrene and 76.5 parts butadiene, parts by weight ofcis-4-poly-butadiene rubber, 25.6 parts by weight of Sundex 790 which isthe trade name for a plasticizer sold by Sun Oil Company, 3 parts byweight of zinc oxide, 2.5 parts by weight ofSunproof Improved which isthe trade name for an antiozonant sold by Uniroyal Chemical Company, 2parts by weight of Wingstay 100 which is the trade name for a stabilizercomprising mixed diaryl-p-phenylene diamines sold by Goodyear Tire andRubber Company, 2 parts by weight It will be seen from the datapresented in the above TABLE I that carbon blacks conventionally madeand sold by Cabot Corporation for use in rubber as reinforcements,bearing the trade name designations of Vulcan 3 through Vulcan 9H carbonblacks, cover the range of HAF type blacks through high structure SAFtype blacks. As shown in the table, the roadwear ratings for theseconventionally available rubber-reinforcing blacks ranges from a low of86% to a high of 103 percent. It has now been shown herein that thenovel blacks of the present invention consistently demonstrate superiorroadwear ratings when compared to the closest available carbon black.The comparison is most suitably accomplished by comparing the roadwearratings for a black of the present invention with a conventional blackhaving a similar iodine surface area.

In order to present a more convenient comparison of the use of theblacks of this invention as rubber blacks with the conventional rubbergrade carbon blacks produced and sold by Cabot Corporation, there arepresented the following two tables. In TABLE II there is shown for eachof the blacks therein a summary of analytical properties. The data onthe more important physical properties attributable to theme of each ofthe blacks in both natural rubber and industry synthetic rubberformulations are presented in TABLE III hereinbelow. The data concerningthe conventional rubber grade carbon blacks is published and distributedwidely by Cabot Corporation and particular emphasis has been placedherein on Technical Report RG-130 entitled Cabot Carbon Blacks in aVariety ofElastomers," published by Cabot Corporation in January 1970.In this technical report. on pages 4 and 6, there is disclosed valuesfor the physical properties of natural and synthetic rubber (SBR)formulations containing all the conventionally available rubber blacks.It is this data sible in all respects. In selecting the control blacks,accordingly, there has been provided a representative group of availableblacks made and sold by Cabot Corporation under the trade name, Vulcan,which are similar in respect to iodine surface areas. This listing ofblacks is sufficiently representative to permit an effective evaluationthereof in the reinforcement of natural and synthetic rubberformulations as demonstrated in TABLE Ill.

TABLE III Physical Properties of Natural and Synthetic RubberVulcanizates Carbon Black Ex. Ex. Ex. x Ex. Vulcan Vulcan Vulcan VulcanVulcan Vulcan Vulcan IRB NATURAL RUBBER RECIPE Tensile, p.s.i. 3720 41104102 4379 400.0 3850 3850 4075 4100 4400 4150 4137 300% Modulus, 28502566 2500 2691 2400 2600 2550 2300 2500 2250 2550 2300 p.s.i.Elongation, 400 463 467 488 470 460 480 530 490 530 5 I 495 ShoreHardness 67 67 66 67 65 67 67 66 67 66 68 67 SYNTHETIC RUBBER RECIPE NO.1 Tensile, p.s.i. 4470 4623 4608 4530 4050 3950 4050 4250 4150 4700 45004251 300% Modulus, 3250 2730 2622 2901 2450 2800 2750 2550 2750 26002800 2456 p.s.i. Elongation, 410 480 480 456 500 470 470 520 490 510 490483 Shore Hardness 67 70 69 67 69 69 68 69 69 71 70 SYNTHETIC RUBBERRECIPE NO. 2

Tensile, p.s.i. 2700 2650 2610 2670 2780 2750 2910 300% Modulus, 1300850 1070 1100 1030 I160 820 I p.s.i. Elongation, 460 650 600 580 590 570630 Shore Hardness 60 l 53 53 55 57 56 Roadwear, ISAF 105 108 100 I00I02 86 93 98 100 I02 I02 103 Carbon Blacks made and sold by CabotCorporation which is reproduced in TABLE III for each of theconventional blacks regarded herein as control blacks. In addition,there is included in TABLES II and III data on Industry Reference BlackNo. 3 (hereinafter referred to as IRB No. 3) inasmuch as this black hasbeen the accepted reference black since June 1970. The data on IRB No. 3reproduced hereinbelow is found in Technical Service Report TG-70-lentitled Industry Reference Black No. 3, written by Messrs. .Iuengel andO- Brien and published by Cabot Corporation on April 1, 1970. Finally,it will be noted that the analytical and physical properties of theblacks of the present invention as described in the following tableshave been disclosed in the examples of this application.

A study of the data presented above reveals that the novel blacks of thepresent invention are generally at least as effective as theconventional rubber grade blacks in reinforcing natural rubbervulcanizates and synthetic rubber vulcanizates. Moreover, while theimportant physical properties of tensile strength, modulus andelongation are maintained at levels equivalent to that obtained with theconventional rubber grade blacks, it is also noted that other desirableperformance characteristics of the rubber compositions of the presentinvention are achieved by the incorporation of the carbon blacks of thepresent invention. In a specific instance herein, a close comparison ofthe black of Example 5 with a conventional Vulcan 5H reveals that theTABLE II Analytical Properties of Carbon Blacks Iodine Tinting CarbonBlack Surface Area, BET Surface DBP Absorption Strength, Tint Tim Samplem /g Area, mlg cc/l00 g SRF Factor Contribution.

Example 1 I29 I46 155 257 313.3 82 Example 2 I03 I Iii I64 242 316 77Example 3 74,6 )2 112 23 314 76 Example 4 69.5 )0 lllll 237 316 75Example 5 78.6 [02 Ill 240 31b 76 Vulcan 3* 82 I02 203 284 71 Vulcan 3H*)0 122 205 291 70 Vulcan 5H* llll I30 225 304 74 Vulcan 6* 98 I18 I15232 291 80 Vulcan 6l-l* I04 116 126 243 302 80 Vulcan 9* H4 142 I14 250300 83 Vulcan 9H* I18 I24 I35 231 286 81 IRB NO. 3 67 82 I00 208 285 73Carbon Blacks made and sold by Cabot Corporation.

In regard to the above TABLE II, it is to be noted that an attempt hasbeen made to compare the novel rubber reinforcing blacks of the presentinvention with conventionally available blacks which are as similar aspostensile strength and modulus of rubber compositions containing theblacks of this invention are indeed highly superior to the use ofconventional rubber blacks. Most importantly, however, it is clearlyevidenced by the data in TABLES l and Ill that a marked improvement inroadwear ratings of treadstocks is achieved by utilizing asreinforcements the blacks of the present invention rather than theconventional rubber grade blacks.

Numerous chemical curing systems have been found useful in promoting theinteraction of the carbon black reinforcement and the natural orsynthetic rubber in practicing the present invention. Exemplary of thechemical curing agents are mercaptobenzothiazyl disulfide (MBTS),N-cyclohexyl-2-benzothiazo|esulfenamide and tetramethylthiuramdisulfide(TMTD). Furthermore, for many purposes, it may be desirable to compoundthe rubber compositions of the present invention with other conventionalrubber additives. lllustrative of such additives are other materialssuch as titanium dioxide, silicon dioxide, zinc oxide, calciumcarbonate, clays, calcium silicate, zinc sulfide, hydrous alumina andcalcined magnesia; thermoplastic resins such as polyvinyl chloride andepoxy resins as compounding substances; vulcanizing agents,vulcanization accelerators; accelerator activators, sulfur curatives;antioxidants; decelerators; heat stabilizers; plasticizers,

softeners or extender oils such as mineral oil, resins fats, waxes,petroleum distillates, vegetable oils, e.g., linseed oil and soybeanoil, di-n-hexyl adipate, trioctyl phosphate, chlorinated hydrocarbons,ether, ketones, terpenes, gum turpentine, rosin, pine tar, coal tarproducts including alkyl naphthalenes and polynuclear aromatics andliquid polymers of conjugated dienes; and the like. It will be apparentthat compositions containing such other additives are within the scopeof this invention.

While this invention has been described with respect to certainembodiments, it is not so limited, and it should be understood thatvariations and modifications thereof may be made which are obvious tothose skilled in the art without departing from the spirit or scope ofthe invention.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

l. A composition of matter comprising a rubber selected from the group'consisting of natural and synthetic rubbers and a carbon black productselected from the group consisting of furnacetype carbon black productscharacterized by having a value for the tint factor relationship of[tint 0.6 (D,,)], wherein D,, is apparent diameter, of at least 311 to3l6, a value for the tint contribution ratio of tint to tint factor ofat least 0.75 to 0.82, a pH value of at least 4, an iodine surface areaof at-least 677to about 145 m /g and a value for the BET total surfacearea of less than 160 m /g, wherein the carbon black product is presentin amounts of from about 10 to about 250 parts by weight per I00 partsby weight of rubber.

2. A composition as defined in claim I wherein the rubber is naturalrubber.

3. A composition as defined in claim 1 wherein the rubber is syntheticrubber.

4. A composition as defined in claim 1 wherein the carbon black productis present in amounts of from about 20 to about 100 parts by weight perI00 parts by weight of rubber.

5. A composition as defined in claim 1 wherein the carbon black productis present in amounts of from about 40 to about parts by weight perparts by weight of rubber.

6. A composition as defined in claim 1 wherein the carbon black producthas a tint contribution ranging from 0.75 to 0.80.

7. A composition as defined in claim 1 wherein the carbon black producthas an iodine surface area ranging from 69 to about 145 m /g.

8. A composition as defined in claim 1 wherein the carbon black producthas an iodine surface area ranging from about 75 to about m /g.

9. A composition as defined in claim 1 wherein the carbon black producthas a pH value ranging from about 6 to about 9.

10. A composition as defined in claim 1 wherein the rubber is acopolymerof styrene and butadiene.

1. A COMPOSITION OF MATTER COMPRISING A RUBBER SELECTED FROM THE GROUPCONSISTING OF NATURAL AND SYNTHETIC RUBBERS AND A CARBON BLACK PRODUCTSELECTED FROM THE GROUP CONSISTING OF FURNACETYPE CARBON BLACK PRODUCTSCHARACTERIZED BY HAVING A VALUE FOR THE TINT FACTOR RELATIONSHIP OFTINT + 0.6 (DA)!, WHEREIN DA IS APPARENT DIAMETER, OF AT LEAST 311 TO316, A VALUE FOR THE TINT CONTRIBUTION RATIO OF TINT TO TINT FACTOR OFAT LEAST 0.75 TO 0.82, A PH VALUE OF AT LEAST 4, AN IODINE SURFAC AREAOF AT LEAST 67 TO ABOUT 145 M2/G AND A VALUE FOR THE BET TOTAL SURFACEAREA OF LESS THAN 160 M2/G, WHEREIN THE CARBON BLACK PRODUCT IS PRESENTIN AMOUNTS OF FROM ABOUT 10 TO ABOUT 250 PARTS BY WEIGHT PER 100 PARTSBY WEIGHT OF RUBBER.
 2. A composition as defined in claim 1 wherein therubber is natural rubber.
 3. A composition as defined in claim 1 whereinthe rubber is synthetic rubber.
 4. A composition as defined in claim 1wherein the carbon black product is present in amounts of from about 20to about 100 parts by weight per 100 parts by weight of rubber.
 5. Acomposition as defined in claim 1 wherein the carbon black product ispresent in amounts of from about 40 to about 80 parts by weight per 100parts by weight of rubber.
 6. A composition as defined in claim 1wherein the carbon black product has a tint contribution ranging from0.75 to 0.80.
 7. A composition as defined in claim 1 wherein the carbonblack product has an iodine surface area ranging from 69 to about 145m2/g.
 8. A composition as defined in claim 1 wherein the carbon blackproduct has an iodine surface area ranging from about 75 to about 135m2/g.
 9. A composition as defined in claim 1 wherein the carbon blackproduct has a pH value ranging from about 6 to about
 9. 10. Acomposition as defined in claim 1 wherein the rubber is a copolymer ofstyrene and butadiene.